JPH0418176B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a flow rate adjustment mechanism for controlling the flow rate of fluid in, for example, a mass flow controller.

Conventional technology and its problems Conventionally, gas measurement and control have been performed using volume flow meters, but recently, with the automation and computerization of manufacturing equipment, mass flow controllers that can perform both measurement and control using electrical signals have been introduced. has become widely used.

In this case, the gas is divided into a sensor section and a bypass section, the flow rate ratio in both is kept constant, and the overall gas flow rate is detected by thermoelectrically detecting the flow rate in the sensor section. . As shown in Japanese Patent Publication No. 54-3743, the bypass section forms a radial flow path by interposing a flow rate adjustment member between a wall section provided in the middle of the flow path and a pressing member. However, the gas flow rate is adjusted in a laminar flow state by changing the cross-sectional area of the radial flow path, but conventional flow path adjustment members are made by arranging a large number of annular thin plates in a laminated manner. This annular thin plate had grooves formed in the radial direction by photoetching.

However, in this case, increasing or decreasing the cross-sectional area of the radial flow path is done by increasing or decreasing the number of thin annular plates, so it is extremely difficult to take them in and out together with the pressing member to select the appropriate number. It was becoming a tedious task.

Means and Effects for Solving the Problems The present invention provides the above-mentioned flow rate adjustment mechanism, in which the flow rate adjustment member is formed with a central axial through hole and a plurality of radial channels at different axial positions. and the opening degree of the radial flow path is adjusted by moving back and forth in the axial direction a plug member that engages with a pressing portion and a threaded portion and has a fitting portion for the through hole of the flow rate adjusting member, Solved the problem.

By moving the plug member forward and backward in the axial direction via the threaded portion, the opening degrees of the plurality of radial flow channels at different axial positions are finely adjusted, and the opening degree of the plurality of radial flow channels at different axial positions is finely adjusted in a laminar flow state depending on the screwing amount of the plug member. In addition, the flow rate can be changed.

Embodiment Hereinafter, a case where an embodiment of the present invention is applied to a mass flow controller will be described based on the accompanying drawings. Note that the examples are merely illustrative, and are not intended to be limiting.

Fluid naturally includes not only gas but also liquid.

In FIG. 1, reference numeral 10 is a primary flow path, and reference numeral 20 is a secondary flow path, which attempts to finely adjust the flow rate of fluid from the primary flow path to the secondary flow path. It is.

Reference numeral 30 is generally called a bypass nut in the technical field of mass flow controllers, and corresponds to the pressing member in the claims, and has a threaded portion 31 at one end which is a large diameter portion.
At the other end (which engages with the female thread 10'), a pressing portion 32 having a smaller diameter is formed, and has a cylindrical portion 33 in the middle.

A suitable number (eight in the example) of through holes 34 are provided in the axial direction inside the threaded portion 31 .

Therefore, the fluid flowing from the left side in FIG. It flows into the flow path 20 (see also FIG. 3).

Reference numeral 40 denotes a flow rate adjustment member that is interposed between the bypass nut 30, which is a pressing member, and a wall portion 20' provided in the middle of the flow path to form a radial flow path. Note that if the wall portion 20' is not provided due to the relationship between the diameters of the primary flow path and the secondary flow path, an annular portion may be provided in the flow path to serve as the wall portion.

A typical example of such a flow rate adjusting member is one in which disks 42 with radial flow passages 41 formed by photoetching are laminated and assembled, as shown in FIG.

This flow rate adjusting member has an axial through hole 43 in the center, and this through hole 43 is adapted to fit with an unthreaded outer peripheral portion (fitting portion) 51 of the plug member 50. . The left side of the plug member 50 has a male threaded portion 52 that engages with the female threaded portion 35 of the bypass nut 30.

When assembling this flow rate adjustment mechanism, the third
As shown in the figure, first, a plug member 50 with an appropriate number of discs 42 screwed into the bypass nut 30 is created.
By fitting this bypass nut assembly into the outer circumferential portion 51 of the flow rate adjusting member 4 and rotating the bypass nut assembly by fitting a tool into the pair of opposing through holes 34 and rotating the bypass nut assembly.
0 is pressed and fixed against the wall portion 20'.

The pressed state is shown in FIG. In this case, since the entire outer circumferential portion 51 of the plug member 50 is fitted with the flow rate adjusting member 40, the radial flow path is almost closed except for a slight gap between the two, and from the primary flow path 10 to the The flow rate of the fluid flowing into the next flow path 20 is almost equal to zero.

Therefore, by inserting a screwdriver from the outside into the groove 53 provided at the left end of the plug member 50 and rotating it in the opposite direction, the plug member 50 can be moved to the left in FIG. The radial flow path of the disk becomes open, a radial flow path is formed here, and fluid can pass from the primary flow path 10 to the secondary side 20. In this way, even if the plug member 50 moves to the left, the flow rate adjusting member 40
Since it is pressed against the wall portion 20' by the bypass nut 30, it will not shift.

Note that if the protruding guide portion 54 is provided on the plug member 50 and the repulsive force by the spring 60 is applied, the plug member 50 once set at a certain position
can be prevented from coming loose.

In addition, since the flow rate adjusting member only needs to have a flow path in the radial direction, it is limited to one in which a groove-like straight radial flow path is formed in a disc as shown in Fig. 4. Of course, it is also possible to form a curved flow path 41' as shown in FIG. Also, as shown in FIG. 6, the through hole 4
1" may be provided.

In addition, since the present invention does not change the cross-sectional area of the flow path by changing the number of disks as in the past, the flow rate adjusting member of the present invention is configured to change the cross-sectional area of the flow path by changing the number of disks. It doesn't have to be layered. It is a member formed on a cylinder with radial through holes provided at different axial positions (i.e., a member formed by molding multiple discs as shown in Figs. 1 and 2 into one). It's okay if there is.

A portion 70 in FIG. 1 is a sensor portion of the mass flow controller, but since this is not the gist of the present invention, a description thereof will be omitted.

Effects of the Invention As explained above, the present invention allows fine adjustment of the flow rate in a laminar flow state by simply moving the plug member forward and backward with a screw, without removing the bypass nut as in the conventional case. It is extremely effective for shortening and automating assembly work, and has an extremely suitable field of application for mass flow controllers and the like.

[Brief explanation of drawings]

The drawings show embodiments of the present invention. Figure 1 is a sectional view of the main parts of a mass flow controller, Figure 2 is a left side view of the main parts of Figure 1, and Figure 3 is a bypass nut, flow rate adjustment member, and plug. FIG. 4 is a front view of the components of the flow rate adjusting member, and FIGS. 5 and 6 are a front view and a perspective view of a modification of the one shown in FIG. 4. 20'... Wall portion, 30... Pressing member, 40
...Flow rate adjusting member, 41...Radial flow path, 43...
...Axial through hole, 50...Plug member, 51...
Fitting portion, 52...threaded portion.

Claims (1)

[Scope of Claims] 1. In a flow rate adjustment mechanism in which a flow rate adjustment member is interposed between a wall portion provided in the middle of a flow path and a pressing member, the flow rate adjustment member has a central axial through hole and an axial direction. By moving a plug member in the axial direction, which has a plurality of radial flow passages with different directional positions, engages with the pressing member through a threaded portion, and has a fitting portion with respect to the through hole of the flow rate adjusting member, A flow rate adjustment mechanism, characterized in that the opening degree of the radial flow path is adjusted. 2. The flow rate adjustment mechanism according to claim 1, wherein the pressing member has a large diameter portion having a threaded portion on the outer periphery and a pressing portion having a smaller diameter than the large diameter portion. 3. The flow rate adjustment mechanism according to claim 1 or 2, wherein a spring repulsive force is applied to the plug member. 4. The flow rate adjustment mechanism according to claims 1 to 3, wherein the flow rate adjustment member is a plurality of discs stacked one on top of the other.